Who tries to stand up for Tom by writing an editorial in the local paper?

Mr. Underwood, the editor of the Maycomb Tribune, is holding a double-barreled shotgun and positioning it out the window of his office. Scout explains earlier that in his position as newspaper editor and writer, Mr. Underwood can report on
"the courthouse and jailhouse news simply by looking out his upstairs window." His office window looks directly out at the jail where the mob has gathered. After the mob disperses, Mr. Underwood tells Atticus that he had him "covered all the time."
In some senses, Scout also "covers" Atticus. She searches for someone in the mob who she knows, and when she realizes that she knows Mr. Cunningham, she speaks to him about his entailment, a legal issue related to land that Atticus is helping him with. She also speaks to Mr. Cunningham about his son, Walter, who attends school with Scout and who Scout and Jem brought home for dinner once. Reminding Mr. Cunningham of his son makes him embarrassed and causes him to think of himself as a father rather than as a member of a vigilante mob going after Tom Robinson. As a result, the energy goes out of the mob, and they disperse.